No worries. I just confused myself trying to figure out what the difference was.
Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.
Benefits of registering include
I think it is more dependent on where you are located. The AP units (inspiration, vision etc) are very popular in Europe, where they are close to the manufacturer. The kiss has been very popular in the UK.
Gareth